Mechanism for releasably locking screen plate in a vat



VAT

R. E. SMITH April 26, 1955 MECHANISM FOR RELEASABLY LOKING SCREEN PLATE IN A Filed June 15, 1954 7 4a WM United States Patent MECHANISM FOR RELEASABLY LOCKING SCREEN PLATE IN A VAT Application June 15, 1954, Serial No. 436,838 3 Claims. (Cl. 92-30) This invention relates to improvements in screens such as used for screening paper making stock and is directed more particularly to mechanism for holding or locking adjacent screen plates in a screen vat.

The principal object of the invention is the provision of locking mechanism for screen plates which is positive in operation and of relatively simple construction so as to be economical in cost.

Heretofore locking mechanism for screen plates have consisted of relatively reciprocable engageable components but have been objectionable in some respects. Pressures used in the clamping and locking operation have been transverse to the components which has resulted in yielding thereof so that the desired pressures have not been attained or maintained.

According to this invention, locking mechanism is provided which has as a prime mover a rotatable shaft with connections to a hold-down member. The components are so adapted and arranged that the shaft is rotatable between clamping and non-clamping positions and as the shaft rotates for clamping certain pivotal connections move past center. In this way, the clamping of the screen plates is not only accomplished readily and easily but the releasing of the platen is accomplished with equal facility, all as will hereinafter appear from the following description.

All of the above objects I accomplish by means of such structure and relative arrangement of parts thereof, as will fully appear by a perusal of the description below and by various specific features which will be hereinafter set forth.

To the above cited and other ends and with the foregoing and various other novel features and advantages and other objects of my invention readily apparent as the description proceeds, my invention consists in certain novel features of construction and in the combination and arrangement of parts as will be hereinafter more particularly pointed out in the claims hereunto annexed and more fully described and referred to in connection with the accompanying drawings where- 1n:

Fig. 1 is a small scale diagrammatic plan view of a screen vat embodying the novel features of the invention;

Fig. 2 is a transverse sectional elevational view through the vat in Fig. 1;

Fig. 3 is a sectional elevational view of Fig. 1;

Fig. 4 is a side elevational view of the mechanism shown in Fig. 3; and

Fig. 5 is a view similar to Fig. 3.

Referring now to the drawings more in detail, the invention will be fully described.

A screen vat is represented by 2 which has opposite and adjacent side and end walls 4 and 6. Screen plates are represented by 8 and as usual are provided with perforations for screening purposes. Said plates have bevelled edges 10 and hold-downs 12 consisting of elongated metal members having edges complemental to the edges of the plates. The vat, of course, may be formed from secured together wood or metal parts.

Elongated beams 14 extend between the walls 4 of the vat and have upper portions for supporting edge portions of adjacent screen plates. These beams may be of any form desired such as channels or the like and have opposite ends secured to the side walls so as to function as struts or supporting beams.

A plurality of books 16 are secured by bolts 17 or on the line 3-3 the like and depend in longitudinally spaced relation from the hold-downs 12.

A shaft 18 is provided which extends along the beam and is rotatable in clamping and non-rotatable directions from clamping to non-clamping positions.

The said shaft 18 may be journalled for rotation in as many members 20 as desired. These members 20 extend between side portions 22 of the beams and are secured to said members 22 by any suitable means such as welding.

Means for connecting the shaft to the hooks 16 consist of tension members or bales 24 and cranks 26. The bales have transverse portions 28 for engaging in the hooks and side arms 30 provided with threaded ends 32 extending through rock shafts 34 oscillatable in the cranks 26. The axes of the rock shafts are disposed radially of the axis of shaft 18.

With the bales engaged in the hooks of the cranks, the shaft 18 and the cranks in upper non-clamping position, the shaft may be rotated in clamping direction. In such rotation, the bales pull downwardly on the hooks so that the hold-down presses on and clamps the adjacent edges of adjacent plates to the beams.

In Figs. 2 and 3 the parts are shown in clamping relation. By rotating the shaft counterclockwise, the hooks and bales may be released.

The parts are so arranged that as the cranks are rotated to clamping position, the pivotal connections of the bales and cranks pass through and slightly beyond a vertical plane extending through the axis of shaft 18 and of the hooks. Thus there is a toggle action for releasably locking the hold down in plate clamping position.

The shaft 18 may be rotated in various ways but for purposes of disclosure, a manually engageable member 40 is secured to one end of said shaft which is rotatable relative to one of the side Walls of the vat.

In Fig. 5 a hook 6' is similar to hook 16 and a bale 24' engageable therewith is pivotally connected to a member 34} whiizh is oscillatable in a crank 26 fixed to a shaft 18.

the parts in clamping relation the hold-down exerts the desired pressure to the screen plates. Adjustments may be made in connection with one hook and in connection with the shaft independently of the others so as to facilitate the distribution of pressure in the manner desired.

As distinguished from apparatus where the clamping action is obtained by a reciprocating of parts the clamping is accomplished by rotation of a shaft thereby to easily and readily obtain the clamping of the screen plates. At the same time releasing of the hold-downs is easily and readily accomplished.

Releasable locking is accomplished by the novel conuction wherein in the clamping movement the pivotal connection of the bale and crank swings through and just past a vertical plane extending through the axis of the shaft and hook of the hold-down.

The invention may be embodied in other specific forms without departing from the essential characteristics there- Patent rotatable relative to said opposite walls and disposed in substantial parallelism with said supporting means, a plurality of connecting means pivotally connected to said shaft on an axis disposed radially of the axis of said shaft adapted to releasably engage said hooks and arranged as said shaft is rotated in one direction to urge said holddown downwardly into plate clamping position.

2. Mechanism for clamping adjacent screen plates having adjacent bevelled longitudinal edges in a vat having opposite and adjacent longitudinal side and transverse end walls comprising, supporting means extending between opposite walls of the vat having upper portions for supporting the bevelled edge portions of adjacent plates in spaced relation, an elongated hold-down having longitudinal side edges complemental to the bevelled edges of the adjacent plates for bearing on and clamping edge portions of said plates to said supporting means, said holddown provided with longitudinally spaced hooks depending from the lower side thereof, an elongated shaft rotatable relative to said opposite walls clamping direction, a plurality of tension members and pivotal connections between inner ends of said members and shaft arranged to provide free outer ends of said members for releasably engaging said hooks, said tension members and pivotal connections being arranged to locate the axes of said connections radially of the axis of rotation of said shaft whereby with the free ends of said members in engagement with said hooks and as said shaft is rotated to clamping position the axis of the connections of the tension members and shaft pass through in clamping and nonand beyond a plane passing through and beyond the longitudinal axis of the shaft and said hooks and the tension members abut said shaft.

3. The combination with a vat having a supporting member for adjacent edges of adjacent screen plates of mechanism for releasably locking said plates to said member comprising, an elongated hold-down for pressing on adjacent portions of said plates having a plurality of hooks depending in spaced relation therefrom, a shaft rotatable relative to said support in clamping and nonclamping directions, plural engageable means for connecting said shaft and hooks each including, a crank fixed to said shaft, a tension member having an end pivotally connected to said crank at a point radially of the axis of. said shaft and a free end portion engageable in said hook, all adapted and arranged whereby as said shaft is rotated in clamping direction with the free end portion in engagement with said hook the axis of the said pivotal connections passes through a plane extending through the axis of rotation of said shaft and the point of engagement of the hook and free end of the tension member and beyond to releasable locking position where the tension member engages a side of said shaft.

Mar. 3, 1903 Mar. 1, 1910 Farnsworth Spring 

